Laserfiche WebLink
12. <br />There is little evidence of any major changes in major ions <br />caused by mining operations. Changes of water quality in the <br />monitoring hole W-2 over the period October, 1980 to July, 1981 <br />are apparent. Example sodium ion concentrations increased from <br />20.7 to 124 mg/L while Ca+2 and HC03- concentrations decreased. <br />This suggests that water of a different type (typical bedrock <br />groundwater) had migrated from the pit into the AVF. <br />It is apparent that precipitation that infiltrates through to <br />the water table will be a Ca- HC03 and possibly Ca-S04 water but <br />' as it infiltrates in the bedrock formation ion exchange pro- <br />cesses cause a reduction in Ca+2 and increase in Na+. <br />' 6.3 TRACE ELEMENT DISTRIBUTION <br />' A detailed examination of trace el ement.chemistry and hydro- <br />geochemical elevation is beyond the scope of this study report. <br />However a few general comments can be made: <br />' 1. pH values are generally neutral, suggesting that the low <br />concentrations of sulphide minerals are adequately buf- <br />fered by calcaKeous minerals in the bedrock. This is a <br />' significant fact as the concentration of heavy metals in <br />the water is very much controlled by pH. <br />' 2. The usual problem ions (Fe, MYS N03-, NH3 and Ba+2) in <br />I coal mines appear to be present in low concentrations <br />that vary little from upstream surface water quality <br />(S-1) and the regional water well (W-7). Ammonia nitro- <br />, gen concentrations are elevated (i.e. above 1 mg/L) in <br />most groundwater samples. However values are generally <br />similar to the regional well W-7. <br />I <br />0 P PIiE AU6 ASSOCiA iES IIMIiEO <br />